WEDNESDAY, Dec. 7, 2016 (HealthDay News) -- When breast cancer spreads to the brain, important molecular changes may occur in the cancer, a small study found.
The discovery of these changes could lead to improved diagnosis and treatment, the researchers said.
About 20 percent of breast cancers are a type known as HER2-positive, which typically respond to targeted therapies. However, HER2-negative breast cancer that has spread to the brain doesn't respond to the same therapies.
In this study, researchers analyzed tumors from 20 patients in the United States and Ireland. They found that primary breast cancer identified as HER2-negative switched to HER2-positive when it spread to the brain.
The findings show that treatments should target not only the original breast cancer, but also brain tumors, said study author Adrian Lee, director of the Institute for Precision Medicine, part of the University of Pittsburgh Medical Center.
"The brain is a common and catastrophic site of metastasis for breast cancer patients," Lee said in a medical center news release. Metastasis is the medical term for cancer spreading to other organs.
"Our study showed that despite the large degree of similarity between the initial breast tumor and the brain metastatic tumor, there were enough alterations to support comprehensive profiling of metastases to potentially alter the course of treatment," he said.
The findings mean "we can screen for presence of HER2 so that we can change and target the therapy to improve outcomes for our patients," Lee said.
The study was scheduled to be presented Wednesday at the San Antonio Breast Cancer Symposium and will be published in the journal JAMA Oncology.
The U.S. National Cancer Institute has more on breast cancer.